Problem regarding PBC registration

Hey guys, I'm ranked D4 this year, and I was trying to sign up for D6. An error came up saying "No D4 players are allowed on this roster."

Yet here's what the CFOA site says:

D-6 (PBC Beginner Division)

Team Entry Fee per Event: $90.00 (HPA included)
Beginner class players, One (1) Rookie class player per team.
Limitations: Novice, Amateur and Pro Players are not allowed. Maximum of 5 players per team. There must be a minimum of 5 teams participating in the event to win prizes. (10yrs and up)

D4 = rookie. Is there an error, or an I really not allowed to be on the D6 team?